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Biomedical subjects

S Medina

Publications and source records attributed to S Medina.

At least 19 recordsLinked to original sources
PubMed2006

[Estimating mortality attribuable to PM10 particles in 9 French cities participating in the European programme Apheis].

The relationship between air pollution and mortality is now admissible with a sufficiently high level of causality proven. This link allows for health impact assessment to be carried out with a significant degree of accuracy, such as the case for the results which are presented here from the nine French cities involved in the Apheis programme. This health impact assessment is based on the methodology developed by the World Health Organization. The number of avoidable deaths is contained between categories ranging from 2.0 to 4.3, 4.0 to 8.9, and from 15.0 to 31.5 per 100,000 inhabitants according to very short term effects, short term effects and long term effects, respectively. There are two scenarios which can be envisioned for the reduction of fine particles levels which are capable of obtaining similar results for both very short term and short term effects. The first involves diminishing the daily concentrations which are above 20 microg/m3 until they reach this value, and the second entails systematically decreasing the daily levels by 5 microg/m3. The first strategy of reducing values to stabilize at 20 microg/m3 has been shown to be the one most favourable and promising for the long term effects. This strategy therefore confirms the reliability and strength of the recommendation formulated at the national level.

Aged↗
PubMed2004

[The impact of air pollution on health. The "Programme de Surveillance Air et Santé 9 villes" (Air and Health surveillance program in 9 cities)].

OBJECTIVES: To quantify the short term effects of air pollution on mortality and hospitalisation for cardiovascular or respiratory disorders in the nine French cities (Bordeaux, Le Havre, Lille, Lyon, Marseille, Paris, Rouen, Strasbourg and Toulouse) of the Surveillance Air et Santé program. METHODS: Data were available on mortality and hospitalisation were available, respectively, from 1990 to 1997 and 1995 to 1999. Exposure data were the concentrations of sulphur dioxide, particles with a diameter of less than or equal to 10 mm, black smoke, nitrogen dioxide, ozone, and carbon monoxide. The analysis assessed the relationships, in each of the cities, between the daily numbers of deaths and hospitalisations and the daily levels of polluting agents, taking into account confounding factors. A combined relative risk was calculated for all the cities. The number of deaths and hospitalisations attributable to air pollution was then estimated for each of the cities, based on the relative risk. RESULTS: Significant relationships were found for mortality, from whatever cause, and for hospitalisations for respiratory disorders in children aged under 15. If the levels of air pollution were reduced to 10 microg/m3 in the nine cities, 2800 premature deaths and 750 hospitalisations for respiratory disorders in children would be avoided, every year. CONCLUSION: Today, it is possible to assess the benefits of reducing air pollution in terms of health in the short term. These analyses would provide a sanitary dimension to the strategies for the reduction of urban pollution on local and European level.

Adolescent↗
PubMed2004

Apheis: public health impact of PM10 in 19 European cities.

STUDY OBJECTIVE: Apheis is a public health surveillance system that aims to provide European, national, regional, and local decision makers, environmental health professionals, and the general public with up to date and easy to use information on air pollution and public health. This study presents the health impact assessment done in 19 cities of Western and Eastern European countries. DESIGN: Apheis developed guidelines for gathering and analysing data on air pollution and the impact on public health. Apheis has analysed the acute and chronic effects of fine particles on premature mortality using the estimates developed by Aphea2 study and two American cohort studies. This health impact assessment was performed for different scenarios on the health benefits of reducing levels of particles less than 10 microm in size (PM(10)). MAIN RESULTS: PM(10) concentrations were measured in 19 cities (range: 14-73 microg/m(3)). The population covered in this health impact assessment includes nearly 32 million inhabitants. The age standardised mortality rates (per 100 000 people) range from 456 in Toulouse to 1127 in Bucharest. Reducing long term exposure to PM(10) concentrations by 5 microg/m(3) would have "prevented" between 3300 and 7700 early deaths annually, 500 to 1000 of which are associated with short term exposure. CONCLUSIONS: Apheis shows that current levels of air pollution in urban Europe have a non-negligible impact on public health, and that preventive measures could reduce this impact, even in cities with low levels of air pollution.

Air Pollutants↗
PubMed2003

Short-term effects of ambient particles on mortality in the elderly: results from 28 cities in the APHEA2 project.

Within the framework of the APHEA2 (Air Pollution on Health: a European Approach) project, the effects of ambient particles on mortality among persons > or = 65 yrs were investigated. Daily measurements for particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) and black smoke (BS), as well as the daily number of deaths among persons > or = 65 yrs of age, from 29 European cities, have been collected. Data on other pollutants and meteorological variables, to adjust for confounding effects and data on city characteristics, to investigate potential effect modification, were also recorded. For individual city analysis, generalised additive models extending Poisson regression, using a locally weighted regression (LOESS) smoother to control for seasonal effects, were applied. To combine individual city results and explore effect modification, second stage regression models were applied. The per cent increase (95% confidence intervals), associated with a 10 microg x m(-3) increase in PM10, in the elderly daily number of deaths was 0.8%, (0.7-0.9%) and the corresponding number for BS was 0.6%, (0.5-0.8%). The effect size was modified by the long-term average levels of nitrogen dioxide (higher levels were associated with larger effects), temperature (larger effects were observed in warmer countries), and by the proportion of the elderly in each city (a larger proportion was associated with higher effects). These results indicate that ambient particles have effects on mortality among the elderly, with relative risks comparable or slightly higher than those observed for total mortality and similar effect modification patterns. The effects among the older persons are of particular importance, since the attributable number of events will be much larger, compared to the number of deaths among the younger population.

Aged↗
PubMed2003

[Urban particulate air pollution: from epidemiology to health impact in public health].

Major air pollution accidents which occurred in the 1950s led to public awareness of the health hazards involved. Since that period, levels of air pollution have decreased, but several studies conducted in North America and Europe indicate that particulate air pollution is linked to increased cardiorespiratory morbidity and mortality. Despite this evidence, several questions were raised concerning the interpretation of the results (threshold effect, harvesting effect and biological plausibility). The aim of this review is to present the link between epidemiological findings and their use in health impact assessment. We review the main causal criteria applied to epidemiology in light of scientific evidence currently available. Some causality criteria are more important than others, but they all support the causal nature of the relationship between air pollution and health, and thus justify the feasibility of health impact assessment calculations. Recent studies on relative risk assessment show that even if the risk linked to worsening air quality is low, public health consequences are high. Such information must be made accessible to policy makers and the population in general so that, together with the public health workers, they can all contribute to improving air quality and health in their communities.

Adolescent↗
PubMed2002

Cerebrospinal fluid levels of thiamine in patients with Alzheimer's disease.

Thiamine is an essential cofactor for several important enzymes involved in brain oxidative metabolism, such as the alpha-ketoglutarate dehydrogenase complex (KGDHC), pyruvate-dehydrogenase complex (PDHC), and transketolase. Some investigators reported decreased thiamine-diphosphate levels and decreased activities of KGDHC, pyruvate-dehydrogenase complex and transketolase in the brain tissue of Alzheimer's disease (AD) patients. We measured cerebrospinal (CSF) levels of thiamine-diphosphate, thiamine-monophosphate, free thiamine, and total thiamine, using ion-pair reversed phase high performance liquid chromatography, in 33 patients with sporadic AD and 32 matched controls. The mean CSF levels of thiamine-derivatives did not differ significantly from those of controls, while the mean plasma levels of thiamine-diphosphate, free and total thiamine were significantly lower in the AD-patient group. CSF and plasma thiamine levels were not correlated with age, age at onset, duration of the disease, and scores of the MiniMental State Examination, with the exception of plasma thiamine-diphosphate with MiniMental State Examination (r = 0.41, p < 0.05) in the AD-patients group. CSF and plasma values did not predict dementia progression, assessed with the MiniMental State Examination scores. These results suggest that CSF thiamine levels are not related with the risk for and the progression of AD.

Aged↗
PubMed2002

Short-term effects of particulate air pollution on cardiovascular diseases in eight European cities.

STUDY OBJECTIVE: As part of the APHEA project this study examined the association between airborne particles and hospital admissions for cardiac causes (ICD9 390-429) in eight European cities (Barcelona, Birmingham, London, Milan, the Netherlands, Paris, Rome, and Stockholm). All admissions were studied, as well as admissions stratified by age. The association for ischaemic heart disease (ICD9 410-413) and stroke (ICD9 430-438) was also studied, also stratified by age. DESIGN: Autoregressive Poisson models were used that controlled for long term trend, season, influenza epidemics, and meteorology to assess the short-term effects of particles in each city. The study also examined confounding by other pollutants. City specific results were pooled in a second stage regression to obtain more stable estimates and examine the sources of heterogeneity. MAIN RESULTS: The pooled percentage increases associated with a 10 micro g/m(3) increase in PM(10) and black smoke were respectively 0.5% (95% CI: 0.2 to 0.8) and 1.1% (95% CI: 0.4 to 1.8) for cardiac admissions of all ages, 0.7% (95% CI: 0.4 to 1.0) and 1.3% (95% CI: 0.4 to 2.2) for cardiac admissions over 65 years, and, 0.8% (95% CI: 0.3 to 1.2) and 1.1% (95% CI: 0.7 to 1.5) for ischaemic heart disease over 65 years. The effect of PM(10) was little changed by control for ozone or SO(2), but was substantially reduced (CO) or eliminated (NO(2)) by control for other traffic related pollutants. The effect of black smoke remained practically unchanged controlling for CO and only somewhat reduced controlling for NO(2). CONCLUSIONS: These effects of particulate air pollution on cardiac admissions suggest the primary effect is likely to be mainly attributable to diesel exhaust. Results for ischaemic heart disease below 65 years and for stroke over 65 years were inconclusive.

Adult↗
PubMed2001

Neuropeptide Y effects on murine natural killer activity: changes with ageing and cAMP involvement.

Changes in the bidirectional interaction between the nervous and the immune systems have been proposed as a cause of ageing. Neuropeptides, such as neuropeptide Y (NPY), could show different effects on immune function with age. In the present work, we have studied the in vitro action of a wide range of NPY concentrations, i.e. from 10(-13) to 10(-7) M, on natural killer (NK) activity, a function which decreases with age. Spleen, axillary nodes, thymus and peritoneum leukocytes from mice of different ages: young (12+/-2 weeks), adult (24+/-2 weeks), mature (50+/-2 weeks) and old (72+/-2 weeks) were used. Stimulation by NPY of NK activity was observed in adult and mature animals in axillary nodes and thymus, and an inhibition in the spleen from young mice. The specificity of the NPY effect on cytotoxic activity was confirmed using a C-terminal fragment of NPY. Furthermore, cAMP levels in leukocytes were found to be decreased by NPY in adult mice, suggesting an involvement of this messenger system in the NK modulation by this neuropeptide.

Aging↗
PubMed2001

Changes with aging in the modulation by neuropeptide Y of murine peritoneal macrophage functions.

Some age-related changes in immune function may be due, at least in part, to a disturbance in the communication between the nervous and immune systems. In the present work, the effects in vitro of neuropeptide Y (NPY) (10(-13) to 10(-7) M) on different peritoneal macrophage functions (adherence to substrate, chemotaxis, phagocytosis, superoxide anion production, and the release of TNFalpha and IL-1beta) have been studied on cells from young (12+/-2 weeks), adult (24+/-2 weeks), mature (50+/-2 weeks) and old (72+/-2 weeks) BALB/c mice. The specificity of these actions was confirmed using two C-terminal fragments of NPY, and the intracellular messengers (protein kinase C and cAMP) involved in the action of the neuropeptide were also analyzed. The results show that the functions studied change with aging and that the effects of NPY on each function, which are carried out through specific receptors, as well as on intracellular pathway, differ depending on age, maintaining the immune functions at physiologically adequate levels in old animals.

Aging↗
PubMed2001

Assessment of deaths attributable to air pollution: should we use risk estimates based on time series or on cohort studies?

Epidemiologic studies are crucial to the estimation of numbers of deaths attributable to air pollution. In this paper, the authors present a framework for distinguishing estimates of attributable cases based on time-series studies from those based on cohort studies, the latter being 5-10 times larger. The authors distinguish four categories of death associated with air pollution: A) air pollution increases both the risk of underlying diseases leading to frailty and the short term risk of death among the frail; B) air pollution increases the risk of chronic diseases leading to frailty but is unrelated to timing of death; C) air pollution is unrelated to risk of chronic diseases but short term exposure increases mortality among persons who are frail; and D) neither underlying chronic disease nor the event of death is related to air pollution exposure. Time-series approaches capture deaths from categories A and C, whereas cohort studies assess cases from categories A, B, and C. In addition, years of life lost can only be derived from cohort studies, where time to death is the outcome, while in time-series studies, death is a once-only event (no dimension in time). The authors conclude that time-series analyses underestimate cases of death attributable to air pollution and that assessment of the impact of air pollution on mortality should be based on cohort studies.

Air Pollutants↗
PubMed2001

Investigating regional differences in short-term effects of air pollution on daily mortality in the APHEA project: a sensitivity analysis for controlling long-term trends and seasonality.

Short-term effects of air pollution on daily mortality in eight western and five central-eastern European countries have been reported previously, as part of the APHEA project. One intriguing finding was that the effects were lower in central-eastern European cities. The analysis used sinusoidal terms for seasonal control and polynomial terms for meteorologic variables, but this is a more rigid approach than the currently accepted method, which uses generalized additive models (GAM). We therefore reanalyzed the original data to examine the sensitivity of the results to the statistical model. The data were identical to those used in the earlier analyses. The outcome was the daily total number of deaths, and the pollutants analyzed were black smoke (BS) and sulfur dioxide (SO(2)). The analyses were restricted to days with pollutant concentration < 200 microg/m(3) and < 150 microg/m(3) alternately. We used Poisson regression in a GAM model, and combined individual city regression coefficients using fixed and random-effect models. An increase in BS by 50 microg/m(3) was associated with a 2.2% and 3.1% increase in mortality when analysis was restricted to days < 200 microg/m(3) and < 150 microg/m(3), respectively. The corresponding figures were 5.0% and 5.6% for a similar increase in SO(2). These estimates are larger than the ones published previously: by 69% for BS and 55% for SO(2). The increase occurred only in central-eastern European cities. The ratio of western to central-eastern cities for estimates was reduced to 1.3 for BS (previously 4.8) and 2.6 for SO(2) (previously 4.4). We conclude that part of the heterogeneity in the estimates of air pollution effects between western and central-eastern cities reported in previous publications was caused by the statistical approach used and the inclusion of days with pollutant levels above 150 microg/m(3). However, these results must be investigated further.

Adolescent↗
PubMed2001

[Surveillance of short-term effects of urban air pollution on mortality. Results of a feasibility study in 9 French cities].

BACKGROUND: This study aims at quantifying air pollution effects on mortality and at evaluating the feasibility of a standardized epidemiological surveillance system of air pollution in 9 French cities. METHODS: Data collection and analysis followed a standardized protocol. Data pollution depended on the development of local air quality surveillance networks (number of indicators, number of stations.). The Generalised Additive Models (GAM) were used to quantify the association between air pollution and mortality. RESULTS: In the 9 studied areas, associations between all causes, cardiovascular and respiratory mortality, and air pollution indicators were observed. These associations were linear without threshold. Depending on the pollutants, excess in mortality related to an interquartile increase in acid-particulate pollution varied between 0.3 and 3.5% for total mortality, 0.5 and 6.3% for cardiovascular mortality, and between 0.1 and 12% for respiratory mortality. Photochemical air pollution varied between 0.4 and 7.3% for total mortality, 1.4 and 6.7% for cardiovascular mortality, and between 1.7 and 30.4% for respiratory mortality. CONCLUSION: In spite of a standardized common protocol, some disparities, inherent to the local characteristics, were noted (length of time series, numbers of ambient urban stations selected and pollutants available.). Nevertheless, this pilot study showed that multicentric epidemiological monitoring of air pollution effects on health was feasible. Yet, this requires to validate the results obtained through a re-analysis of the mortality data on a longer period of study. It also requires to study the feasibility and the relevance of the use of other health indicators, such as hospital admissions.

Air Pollution↗
PubMed2001

[Short-term relationships between urban atmospheric pollution and respiratory mortality: time series studies].

Time series studies conducted in the field of air pollution aim at testing and quantifying short-term relations which can exist between daily air pollution levels and daily health effects. The method used for this type of survey has sometimes been misunderstood mainly because individual factors and indoor exposure to air pollutants were not taken into account. The adjustment on these individual confounding factors commonly used in classic epidemiologic studies (case-control studies, cohort studies) is not adequate to times series studies which are based on aggregate data. This is different for those factors that change over time according to the levels of air pollution (meteorological conditions, influenza epidemics, trend of health cases) which, when being analysed, must be taken into account either indirectly through time modelling or directly through non-linear modelling processes. During this last decade, numerous studies using the time series method have been published and have found short-term associations between daily levels of air pollution commonly observed and daily respiratory mortality. The consistency of the numerous results published in the international literature are more arguments in favour of non-confounding short-term relations between air pollution and respiratory mortality.

Adult↗
PubMed2000

The NPY effects on murine leukocyte adherence and chemotaxis change with age. Adherent cell implication.

The two-way communication between the nervous and immune system is currently well-known, but the age-related changes in this communication have been scarcely studied. In the present work, we have investigated the in vitro effects of neuropeptide Y (NPY) at concentrations ranging from 10(-13) to 10(-7) M on the adherence and chemotaxis capacities of spleen, axillary node, thymus and peritoneum leukocytes from BALB/c mice. The NPY effect on these functions was examined on cells from animals of four different ages, i.e. young (12+/-2 weeks old), adult (24+/-2 weeks old), mature (50+/-2 weeks old) and old (72+/-2 weeks old). In young animals, NPY stimulates the adherence of leukocytes from spleen, axillary nodes and thymus and inhibits it in cells from peritoneum. In adult animals NPY inhibits the adherence of leukocytes from thymus. These effects disappear with ageing in all locations. Chemotaxis is stimulated by this neuropeptide at all ages in cells from axillary nodes and peritoneum, but this effect is absent in old mice. NPY exerts an inhibitory effect on the chemotaxis of leukocytes from thymus at all ages studied. These NPY effects on leukocytes seem to be carried out through adherent cells.

Aging↗
PubMed2000

Effect of aging on the modulation of macrophage functions by neuropeptides.

The existence of a functional connection between the nervous and the immune system is supported by increasing recent evidence. In previous work we have shown that peptides from the nervous system, such as gastrin-releasing peptide (GRP), neuropeptide Y (NPY) and sulfated cholecystokinin octapeptide (CCK-8s), have modulatory effects on the immune functions in adult animals. Since the immunodepression found in aging organisms may be related to changes in the neuroimmune network, the aim of the present work was to study the changes with aging in the effect of CCK-8s, GRP and NPY on peritoneal macrophage functions (adherence to tissues, mobility, ingestion of foreign particles and superoxide anion production) from BALB/c mice of three different ages: adult (24+/-2 weeks old), mature (50+/-2 weeks old) and old (72+/-2 weeks old). The results show that the increase in adherence capacity produced by neuropeptides in cells from adult and mature animals disappears in old mice. The stimulatory effect of GRP and NPY on mobility, ingestion and superoxide production in macrophages from adult mice disappears (GRP) or changes to inhibition (NPY) in cells from old animals. The decrease of these functions caused by CCK-8s in adult or mature animals continues in old mice. These data suggest that the modulation by neuropeptides of the macrophage function changes with the age of animals.

Aging↗